Exam 1
What is the element in the fourth period and seventh group? What state does it exist in naturally?
Bromine, liquid
What is the difference between endothermic and exothermic?
Endothermic takes in heat. Exothermic releases heat.
What is electronegativity? What is the most electronegative element?
The ability of an atom within a molecule to attract valence electrons toward itself. Fluorine
What is the cubic lattice?
The basic repeating unit of the structure of a compound.
What is the characteristic of a precipitation reaction?
Pairs of insoluble ions make a precipitate (solid)
What is the internal energy?
Sum of all kinds of energy which can be transferred as heat or work. It is a state function.
What is the formula for formal charge and why is it important?
Tells us which structure is best. Valence electrons - number of lone pairs - one electron per bond pair.
What is an electrolyte? What makes is strong or weak?
An electrolyte is an ion or compound that is dissolved in solution which conducts electricity. A strong electrolyte will dissolve completely and a weak one will not.
What is the difference between an isomer and isotope?
An isotope is different numbers of neutrons. An isomer is same chemical formula but different spacing or structure.
What are some rules of standard enthalpy of formation?
Enthalpy change associated with formation of one mole of substance. Use standard states of atoms/elements and may need to use fractions.
If a molecule has five groups and two lone pairs, what is its molecular shape? What are these angles?
T-shaped
90 and 180
What is vapor pressure and how does it relate to boiling point?
Vapor pressure is when liquid molecules overcome intermolecular forces to become gas. The boiling point of a liquid occurs when the vapor pressure of the liquid is equal to the external pressure around it.
Classify the following acids as monoprotic, diprotic, and triprotic. Which are weak acids?
phosphoric acid, HBr, HNO3, sulfuric acid, hydrofluoric acid, CH3COOH
phosphoric acid- weak, triprotic
HBr- strong, monoprotic
HNO3- strong, monoprotic
sulfuric acid- strong, diprotic
hydrofluoric acid- weak, monoprotic
CH3COOH- weak, monoprotic
What are the three components of the particle nature of light? Describe them.
Blackbody radiation- heating up an object will allow it to increase in kinetic energy and emit light at quantized values.
Photoelectric effect- kinetic energy of electrons is released when light is directed at metal plates
Emission of light from hot elements- heating solid, liquid, or condensed gas at high temperatures can result in continuous emission spectra
What is lattice enthalpy?
The enthalpy change that occurs when one mole of ionic solid separates into gaseous ions. Always endothermic and breaking ionic bonds.
What are the four colligative properties? What is a colligative property?
Vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. A colligative property is given to solutions where the chemical nature of the solute and solvent does not alter the solution.
Explain a reduction-oxidation reaction. What does "oxidation" and "reduction" mean?
It is the transfer of electrons between ions. Oxidized means it becomes more positive and loses electrons. Reduced means it becomes more negative and gains electrons.
List the different atomic orbitals and their corresponding quantum numbers. What are their allowed values? How would you write an electron configuration?
Principal (n) is orbital size in positive integers
Angular momentum (l) is orbital shape in integers from zero to n-1
Magnetic (ml) is orbital orientation in integers from -1 to 0 to +1
Spin (ms) is direction of electron spin in plus or minus one half
Write electron configuration according to periodic table map. Each electron has a different set of quantum numbers.
What are the limitations of hybridization theory?
Describe molecular orbital theory. Be sure to include bonding/antibonding wave functions and electron density.
Doesn't explain resonance structures/delocalized electrons and magnetism.
Electron orbitals are delocalized over the entire molecule. A bonding molecular orbital is formed by wave functions that reinforce each other and yield a region of high electron density between nuclei. An antibonding wave function results in a node of zero electron density between nuclei.
What are intermolecular forces? Name at least four and their definitions.
Forces between molecules or ions, not the bonds held within them.
Ion dipole, hydrogen bond, dipole dipole, ion-induced dipole, dipole induced dipole, and London dispersion forces.